Fastener cap



Oct. 19, 1965 MITCHELL ETAL 3,213,189

FASTENER CAP Filed April 2, 1963 F23 1. 1g a s 3g /4 F a 40 qin H I! I'll A ll lill \g 63 40 56 fg-ee 32 I 20 lo l Inversion 2'; Edward B. Mitchell 5 .4 12021422? Fraser, M Z y MAM nw wm United States Patent M 3,213,189 FASTENER CAP Edward B. Mitchell, Wohurn, and Robert W. Fraser,

Framingham, Mass., assignors to United-Carr Incorporated, a corporation of Delaware Filed Apr. 2, 1963, Ser. No. 270,074 1 Claim. (Cl. 174138) This invention relates generally to fastening devices and more specifically to fastening devices for use with snap switches and the like.

An object of the present invention is to provide a fastening device having means of engaging an article to be held and having other means for engaging an apertured support.

A still further object of the invention is to provide a means of engaging an apertured support in a fastening device which will operate independent of the remaining portion of the fastening device.

Another object of the invention is to provide a fastening device utilizing legs which have means for engaging an article to be held and also means of engaging an apertured support.

A still further object of the invention is to provide a snap switch having engaged therewith a plastic fastener which provides a portion of the housing of the switch and also provides means of engaging and holding internal elements of the housing of the switch in alignment as well as engaging an apertured support.

Other objects will, in part, be obvious and will, in part appear hereinafter.

In the drawings:

FIG. 1 is a side elevation of the fastener;

FIG. 2 is a bottom plan of the fastener shown in FIG. 1;

FIG. 3 is a top plan view of the fastener engaged to a switch and to an apertured support;

FIG. 4 is a section taken on line 44 of FIG. 3;

FIG. 5 is a section taken on line 55 of FIG. 3, the bottom portion broken off; and

FIG. 6 is a section taken on line 6-6 ofFIG. 4.

There is shown in the drawings a switch comprising a plunger 10, a housing 12, a fastening device 14, a spring 16, a movable contact 18 and a pair of fixed contacts 20.

The plunger 10 comprises an elongated tubular body closed at one end, and open at the other, and a pair of rectangular tabs 11 formed proximate the open end of the plunger 10 on the external surface thereof. The tabs 11 are in spaced parallel relation to each other on opposite sides of the plunger 10 and extend beyond the end of same.

The housing 12 comprises a wall 22 defining a cavity 24. The wall 22 has a series of four grooves formed therein, one on each quadrant of the cavity 24. A series of four channels 28a, 28b, 28c and 28d are formed one between each two grooves on a plane spaced from the plane of each of the channels 28a, 28b, 28c, and 28d and closer to the axis of the housing 12. The pairs of channels 28a, 28b, 28c, and 28d are in spaced parallel relationship with each other and form a T-slot with one of the grooves. In other words there are four channels 28a, 28b, 28c, and 28d. The channels 28:: and 2812 are in spaced parallel relationship with each other and are separated from one of the grooves by a thin wall which overlies a portion of the groove. The combination of the channels 28a and 28b and the groove form a T-slot. This same result is also reached with the channels 280 and 28d and their respective groove as shown in FIG. 6. One end of the housing 12 is partially closed by a bridge element 30 and the bridge element 31) forms a pair of slots 32 with a portion of the wall 22. A protuberance 3,213,189 Patented Oct. 19, 1965 23 is formed on the bridge element 30 directed toward the cavity 24.

The fastener device 14 which may be formed of a plastic material, comprises a circular flat base portion 36, having a wall defining an aperture 38 through said base portion 36, having a center coincident with the midpoint of the base portion 36. A pair of legs 40 are formed integral with the base portion 36 extending away from the plane thereof. A portion of each of the legs 40 are in spaced parallel relationship with each other as shown in FIG. 1. Each of the legs 40 comprises a terminal end bent back on the remaining portion of the legs 40 to form an engagement end 42. A notch 44 is formed on the inner surface of the leg 40 a predetermined distance from the undersurface of the base portion 36. The engagement ends 42 are formed by the legs 40 away from the central line of the fastening device 14 then back toward the remaining leg portion. The notches 44 are in substantially opposed relationship.

Each of the fixed contacts 20 comprises a base element 46 having one of its terminal ends bent into a contact portion 48 which is again bent to form a termination point 50. The contact portion 48 is in angular relationship with the base element 46, and the termination portion is integral with the contact portion 48 and in spaced substantially parallel relationship to the plane of the base 46 as shown in FIG. 5. At the opposite end of the base element 46 from the termination portion 50 an offset spade termination 52 is formed having a configuration old and well known in the art as shown in FIG. 4.

The movable contact 18 comprises a dome-shaped element 54 having a circumferential winged portion 56 extending from the edge thereof and circumscribing the said dome-shaped element 54 as shown in FIG. 5. In cross section the movable contact 18 will then present a sinuous curve.

The elements are combined in the following manner to provide the switch. Each of the slots 32 comprises an extension of one of a guide channel and one of the fixed contacts 20 is inserted into the guide channel which is formed by the channels 28a and 28b for example. The spade termination 52 is passed into the two channels 28a and 28b and down through the slot 32 to extend beyond the end of the housing 12. The base element 46 of the fixed contact 20 rests against the base of the groove formed adjacent the guide channel. The contact portion 48 and the termination portion 50 extend into the guide channel between its two forming channels 28a and 28b for example. The same engagement is made with the other fixed contact 20 on the opposite side of the housing 12 placing the two spade terminations in spaced parallel relationship with each other and also the two contact portions 48. The groove opens into the guide channel to allow passage of the fixed contact through the slot 32. A helical compression spring 16 is now placed within the housing 12 and a terminal end of the spring 16 circumscribes the protuberance 23 formed on the bridge element 30 thereby placing the axis of the spring 16 coincident with the axis of the housing 12. The dome-shaped element 54 of the movable contact 18 is placed at the other end of the spring 16 with the end portion of the spring 16 circumscribing the dome-shaped element 54. That end portion of the spring 16 in turn is circumscribed by the wing portion 56 of the movable contact 18. In this position the wing portion 56 is in abutting relationship with the contact portion 48 of the fixed contacts 20 as shown in FIG. 5.

The fastening device 14 may have a washer element 58 extending from the base portion 36 between the two legs 40. The washer element 58 has a pair of openings in opposed relation spaced from each other to accept the tabs 11. A collar element 60 consisting of two extensions formed on opposite sides of the external surface of the housing 12 are formed to create shoulder areas 62. The plunger is now passed up between the legs 40 and through the aperture 38 in a manner which places each of the tabs 11 into one of the openings formed in the washer element 58 so that the upper portions of each of the tabs 11 are in abutting relationship to the base portion 36 with the major portion of the plunger 10 extending beyond the base portion 36 in the opposite direction from the legs 40. A plane drawn through the midpoint of the legs 40 would be at right angles to a plane drawn through the midpoint of the fixed contacts 20 when the switch is fully assembled. The edge of the tubular plunger 10 rests on the arcs formed at the juncture of the wing portions 56 and the dome-shaped element 54 of the movable contact 18.

The fastening device 14 can then be engaged to the housing 12 by snapping the legs down over the collar element 60 of the housing 12. The collar element 60 will fit into the notch 44 with the lower shoulder of the notch engaging the shoulder 62 of the collar element 60. At the same time the tabs 11 of the plunger will slide into the openings formed in the washer element 58 and with the movable contact 18 held in position by the lower end of the plunger 10 the fastening device effectively locks all the elements of the switch together.

To engage the fastener switch assembly to an apertured support 64, the switch is passed down through the aperture formed in the support until the base portion 36 of the fastening device 14 lies in superposed abutting relation with the upper surface of the support adjacent to the aperture. At the same time the engagement end 42 of the legs 40 have been compressed toward the axis of the aperture and the fastening device until the abutting engagement is made between the base portion 36 and the support 64. A series of notches may be cut on an ex ternal surface of the engagement end 42 to increase the locking action between the engagement end and the wall of the aperture formed through the support 64. In relaxed position the knuckle diameter of the engagement end 42 is greater than the diameter of the aperture, so that on engagement the engagement end 42 of the legs 40 will be kept under a compressed stress thereby forming a secure locking engagement.

The particular embodiment shown in FIGS. 1 through is referred as a normally on switch. In order to construct a switch which would be normally off, the wing portions 56 of the movable contact 18 would be flared upward instead of downward and the contact portion 48 of the fixed contacts 20 would be formed so as not to contact'the wings 56. Tabs would then be stuck out somewhere within the cavity 24 from the base element 46 of the fixed contacts 20 so that compression of the plunger would place the wings 56 into electrical engagement with the struck out tabs.

Since certain other obvious modifications may be made in this device without departing from the scope of the invention, it is intended that all matter contained herein be interpreted in an illustrative and not in a limiting sense.

We claim:

A one piece fastener formed of an insulating material and adapted for coupling the components of an article and for securing the article to an apertured support comprising a base having an aperture therethrough, an integral washer adjacent the underside of the base, said washer having opposed internal edges, portions of which are coincident with the edges of said base defining said aperture, and other portions of which are laterally offset from said aperture to provide a pair of opposed slots for receiving portions of a component of the article in abutting relationship with said base, and a pair of flexible legs depending from said base, each of said legs having a portion thereof integral with said base and said washer, a free, terminal, support-engaging end proximate to and spaced from said base and an inwardly extending shoulder spaced from said washer and co-operating therewith to define a pair of opposed notches for receiving another component of the article, the distance between the outer, lateral extremities of each of said legs being greater than the diameter of the aperture in the support such that upon insertion of said fastener into the aperture in the support said legs will be flexed inwardly toward the axis of the aperture in said base and will engage the support under a compressed stress thereby positively securing the article to the support.

References Cited by the Examiner UNITED STATES PATENTS 955,521 4/10 Lovejoy 248-27 2,236,496 4/41 Beggs 248-27 2,446,141 7/48 Parsons 200-168 2,585,887 2/52 Woodward 248-27 2,798,271 7/57 Flora 248-27 X 2,889,125 6/59 Hart 248-27 2,936,437 5/60 Fraser et al. 339-128 X 3,035,624 5/62 Jaworski -80 3,079,581 2/63 Klumpp 174-153 X 3,101,922 8/63 Moody et al. 248-27 FOREIGN PATENTS 357,786 12/61 Switzerland.

JOHN F. BURNS, Primary Examiner.

BERNARD A. GILHEANY, LARAMIE E. ASKIN,

Examiners. 

